CN101852887A - Optical fiber and fiber device that chromatic dispersion is arranged - Google Patents

Optical fiber and fiber device that chromatic dispersion is arranged Download PDF

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Publication number
CN101852887A
CN101852887A CN201010128672A CN201010128672A CN101852887A CN 101852887 A CN101852887 A CN 101852887A CN 201010128672 A CN201010128672 A CN 201010128672A CN 201010128672 A CN201010128672 A CN 201010128672A CN 101852887 A CN101852887 A CN 101852887A
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optical fiber
order mode
mould
dispersion
wavelength
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西达尔斯·拉马钱德兰
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Furukawa Electric North America Inc
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02214—Optical fibres with cladding with or without a coating tailored to obtain the desired dispersion, e.g. dispersion shifted, dispersion flattened
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/0208—Refractive index modulation gratings, e.g. Bragg gratings characterised by their structure, wavelength response
    • G02B6/02085—Refractive index modulation gratings, e.g. Bragg gratings characterised by their structure, wavelength response characterised by the grating profile, e.g. chirped, apodised, tilted, helical
    • G02B6/02095—Long period gratings, i.e. transmission gratings coupling light between core and cladding modes
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
    • G02B6/03644—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - + -
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03688—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 5 or more layers
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29371—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion
    • G02B6/29374—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating principle based on material dispersion in an optical light guide
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
    • G02B6/02009—Large effective area or mode field radius, e.g. to reduce nonlinear effects in single mode fibres
    • G02B6/02023—Based on higher order modes, i.e. propagating modes other than the LP01 or HE11 fundamental mode
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/26—Optical coupling means
    • G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
    • G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
    • G02B6/29304—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by diffraction, e.g. grating
    • G02B6/29316—Light guides comprising a diffractive element, e.g. grating in or on the light guide such that diffracted light is confined in the light guide
    • G02B6/29317—Light guides of the optical fibre type

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
  • Optical Integrated Circuits (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)

Abstract

Optical fiber and fiber device that chromatic dispersion is arranged.The application discloses the fiber device that includes optical fiber, and this optical fiber has the total dispersion greater than material dispersion, and has the optimum dispersion value less than+50ps/nm-km.When light resides in the single high-order mode of optical fiber, LP typically basically 02In the time of on the mould, obtain the dispersion values of expectation.This optical fiber also advantageously has the significant interval between the refractive index of high-order mode and any other mould.

Description

Optical fiber and fiber device that chromatic dispersion is arranged
The application is to be that March 2, application number in 2007 are 200710084442.9, denomination of invention is divided an application for " optical fiber and fiber device that chromatic dispersion is arranged " a case the applying date.
Technical field
The present invention relates to fiber device, wherein the total dispersion of this device is greater than material dispersion.
Background technology
Optical fiber can guide the light of a plurality of space diagrams, and each space diagram quilt is the transverse mode of called after optical fiber (following in order to simplify, as to claim that it is a mould) uniquely.The dispersion characteristics of fiber middle light signal depend on the mould that it is being propagated.Therefore, the feature of every kind of mould is its distinctive dispersion values.The chromatic dispersion of mould is substantially equal to material dispersion (D m) and waveguide dispersion (D w) sum.Material dispersion be light signal resident material dispersion, that is, make the material (the most generally, trace germanium being arranged, phosphorus, the quartz of fluorine and other adulterants) of optical fiber.Waveguide dispersion is because the index distribution of qualification fibre-optic waveguide causes.Therefore, (it changes D to the index distribution by changing optical fiber suitably w), can design the chromatic dispersion (D of mould Total=D m+ D w).As explained below, in most optical fiber designs, waveguide dispersion D wIt is negative value.Therefore, the index distribution of optical fiber can be designed to obtain D wVery big negative value is arranged, thereby can realize the fibre-optical dispersion D of various different negative values Tota, and in the attainable chromatic dispersion of maximum, most of CHROMATIC DISPERSION IN FIBER OPTICS are material dispersions.For the quartz that various adulterants are arranged, under the wavelength greater than 1300nm approximately, its D m＞0, and under the wavelength less than 1300nm, its D m＜0.Therefore, under the wavelength greater than 1300nm, most of optical fiber can be realized positive or negative chromatic dispersion (D Total), and under the wavelength less than 1300nm, fibre-optical dispersion only may be D Total＜0.
The photoresponse of light pulse in optical fiber depends primarily on the chromatic dispersion that it stands.This is for all being correct such as the linear effect of pulse expansion with such as the nonlinear effect that pulse distortion and orphan form.Therefore, CHROMATIC DISPERSION IN FIBER OPTICS plays a key role in design optical fiber based devices.Though optical fiber telecommunications system is usually operated in the wavelength coverage between 1300nm or 1500nm and the 1650nm, many other important optical systems are to work under lower wavelength.The preferred operation wavelength of fiber laser is at 1060nm.Ubiquitous titanium-doped sapphire laser can be used on several pumps and surveys in experiment and biomedical imaging or the treatment, and it is usually operated in the wavelength coverage of 700nm to 1000nm.At last, all wavelengths that human eye can be seen, therefore, such as the wavelength of several commercialized device work of laser designator, their wavelength coverage is from 400nm to 700nm.Common operation wavelength all was below 1300nm during all these were used, and wherein silica fibre only produces negative chromatic dispersion.Have the optical fiber of positive dispersion or zero chromatic dispersion can propagate the orphan and produce broadband super continuum light spectrum in these wavelength coverages, for example, it is useful for the biomedical imaging system.In many this systems, under these wavelength, require positive low dispersion fiber.Therefore, we need such optical fiber, and it can provide stable light pulse propagation under less than the wavelength of 1300nm, its chromatic dispersion be on the occasion of, and can regulate by the appropriate designs index distribution.We need a kind of like this optical fiber, in any required wavelength coverage, and its waveguide dispersion D wCan be designed to greater than zero.
Most of optical fiber are single-mode fibers, this means that these optical fiber only support the basic mode of lowest-order, and basic mode is labeled as LP 01Mould.In the subscript two numerals representation space light figures respectively have the number of minimum of intensity (zero) in along azimuth direction (first subscript) and radially (second subscript).As mentioned above, LP in the standard quartz optical fiber 01Mould only can be realized D w＜0, wherein index distribution is to be determined by the various adulterants in the quartz.Therefore, whole this type optical fiber can have maximum D Total=D m, D wherein mIt is quartzy material dispersion.Since under the wavelength of＜1300nm, D m＜0, in this wavelength coverage, can not realize D Total＞0.
The optical fiber (below be referred to as air-silica fibre) that comprises core is the longitudinal extension along this fiber axis, the IEEEPhotonics Technology Letters that it has J.C.Knight and works together and publish in July, 2000, Volume 12, interesting character described in the page 807, its title are " Anomalous Dispersion in Photonic Crystal Fiber ".They illustrate that air-silica fibre can realize big positive dispersion in any wavelength coverage.Yet the chromatic dispersion of air-silica fibre and their mould district are closely connected, and it can not realize high chromatic dispersion and very big effective mould district is arranged, and therefore, this design space only can be used on and requires to have in high positive dispersion and the low nonlinear system.In addition, we know that this optical fiber has big birefringence and loss, and they are reduced in the use in the real system greatly.And all solid state optical fiber that utilizes routine techniques to make always has lower cost than the optical fiber that requires artificial assembling fibre-optical preform (as the situation at air-silica fibre).Also there is terminal problem in this optical fiber: cause loss with the splicing of other optical fiber, and the variation of light property, and can not make reliably.
Lysiansky, Rosenblit and Wei disclose another kind of technology to obtain D w＞0.At US Patent No.6, in 724,694, the typical index that they disclose a kind of solid-state (that is, not being air-quartz) optical fiber distributes, and this optical fiber is supported LP 01Mould and high-order mode (HOM), the wherein LP of waveguide design generation 02Mould or LP 03The chromatic dispersion of mould is greater than+50ps/nm-km.Yet these designs can not realize zero or low positive dispersion value in the wavelength coverage of＜1300nm, and therefore, it can not be used for the application that produces such as orphan's compression and super continuum light spectrum, and these use the laser instrument that normally utilizes the 700-900nm wavelength coverage interior.In addition, these HOM optical fiber have the critical defect that most of optical fiber are supported multimode.Though we wish that light resides among the required HOM substantially,, existing other mould to make this design is responsive for mode coupling, and light can lose in the mode coupling process and maybe can cause harmful interaction noise problem.This mode coupling is the effective refractive index (n with required mould and any other mould Eff) reducing of difference and increase.The disclosed design space of above-mentioned author causes LP 02Mould and LP 11Mould has identical n under operation wavelength EffTherefore, these designs are responsive especially for interaction noise and loss.
Therefore, we need a kind of optical fiber that can utilize conventional manufacturing technology to make, it has such index distribution, not only produces the positive dispersion of any size in various wavelength coverages, but also can guarantee that the mode spacing in this optical fiber is insensitive for mode coupling.
Summary of the invention
The present invention relates to include the fiber device of optical fiber, the index distribution that this optical fiber has can produce D in any wavelength coverage Total＞D m, it makes D Total＜+50ps/nm-km, this character is desirable at the nonlinear various fiber devices that utilize light.If light resides on the single high-order mode (HOM) of optical fiber basically, then above-mentioned index distribution produces given dispersion values.Usually, this HOM is the LP of optical fiber 02Mould, still, the professional should be known in the HOM that can expand to this design other, for example, LP 11Mould or LP 03Mould.We illustrate typical index distribution, and it has very little positive dispersion D in the wavelength coverage of 820-900nm and 1040-1160nm Total(＜+50ps/nm-km) because these wavelength coverages are significant especially for the nonlinear optical fiber optical devices, in these wavelength coverages, common silica fibre has D just Total＜0, thus excitation needs other scheme.
Also open herein a kind of like this index distribution, it produces D in any wavelength coverage Total＞D m, and do not retrain chromatic dispersion D TotalSize, propagate but produce signal stable and that do not have Mode Coupling simultaneously.In order to realize this back one feature, optical fiber designs is limited to such optical fiber, the n of wherein required HOM and any other mould EffPoor (below be labeled as Δ n Eff) absolute value greater than 10 -4The optical fiber of our disclosed design can be realized D herein Total＞0 and Δ n EffAbsolute value＞10 -4, it can be applied to the various fiber devices in the wavelength coverage of＜1300nm, and the bulk optics device is only arranged at present.
The invention still further relates to a kind of D that is used to obtain Total＞D mEquipment, comprising: optical fiber and at least one weighted-voltage D/A converter, be used for input light is converted to the desirable HOM of optical fiber, therefore, the propagation of light occurs on the desirable pattern substantially.In some cases, this device also is included in the weighted-voltage D/A converter of this device output terminal, in order that the light of the Gauss's space diagram that obtains being familiar with from the output of this device.
In one embodiment, weighted-voltage D/A converter is static or tunable long period fiber grating.
Description of drawings
Fig. 1 illustrates the index distribution of support more than the optical fiber of a mould;
Fig. 2 illustrates the LP of the described optical fiber of Fig. 1 02The chromatic dispersion of mould 20 is as the function of wavelength;
Fig. 3 illustrates the index distribution of support more than the optical fiber of a mould, and still, it is designed to produce LP 02The D that mould is required Total, meanwhile, guarantee that also light signal is stable with respect to mode coupling;
Fig. 4 illustrates the LP of waveguide described in Fig. 3 02The chromatic dispersion D of mould Total
Fig. 5 illustrates two not isotype effective refractive index n of optical fiber shown in Figure 3 Eff
Fig. 6 illustrates the index distribution of finished product fibre-optical preform, and it produces LP 02Mould;
Fig. 7 illustrates the LP of optical fiber shown in Figure 6 02Chromatic dispersion (the D of mould Total);
Fig. 8 illustrates LP respectively 02Mould (80) and LP 11The n of mould (81) EffAnd
Fig. 9 (a), 9 (b) and 9 (c) illustrate several sketches of exemplary device.
Embodiment
Fig. 1 expresses support for the index distribution of the optical fiber of a plurality of moulds, and still, this optical fiber designs becomes to produce LP 02The D that mould is required TotalThis index distribution comprises: extending to radial position is the fibre core 10 of 1 μ m, and its Δ N equals 0.039; Below be that thickness is the irrigation canals and ditches district (ring mixes down) 11 of 0.5 μ m, its Δ N equals-0.008; Below be that thickness is the ring 12 that mixes of going up of 1.4 μ m, its Δ N equals 0.027.After this, the fibre cladding of only being made by quartz glass 13 extends to the glass-clad edge of this optical fiber.In typical optical fiber, the glass-clad of optical fiber extends to the radial position of 62.5 μ m.Index distribution shown in Fig. 1 only arrives the radial position of 7 μ m, because the remainder of optical fiber only is the extension of quartz glass covering.The feature of index distribution is to represent with Δ N, and Δ N is the refringence between useful zone and the quartzy covering.
Fig. 2 represents the LP of optical fiber shown in Figure 1 02The chromatic dispersion of mould 20 is as the function of wavelength.Also the draw material dispersion of quartz (21) of Fig. 2, it has very big negative value in the wavelength coverage of 820-900nm.As reference, Fig. 2 also draws and represents the dotted line (22) of zero dispersed lines.From this figure as can be seen, the LP of this optical fiber 02Mould has very big waveguide dispersion D wThis is because the chromatic dispersion (D of this mould Total) be 0 and pact+5ps/nm-km between change, and in this wavelength coverage, the material dispersion D of medium mBe-78ps/nm-km and-change between the 109ps/nm-km.Because D Total=D m+ D w, and D mVery big negative value is arranged, D wMust have very big on the occasion of, in order that make D TotalVery little positive dispersion is arranged.
Those skilled in the art will understand that, the waveguide dispersion of medium is a constant with respect to the complementary ratio of waveguide dimensions and operation wavelength, as at Synder and Love at Optical WaveguideTheory, Chapman and Hall, New York, described in detail in 1983.The notion of complementary ratio is, waveguide dimensions and operation wavelength under the certainty ratio, this waveguide has roughly the same waveguide dispersion D wTherefore, those skilled in the art will understand that, though the optical fiber that Fig. 1 describes is the very little positive dispersion of generation in the wavelength coverage of 800-900nm,, the radial dimension that suitably disposes index distribution can produce similar waveguide, the LP of this waveguide under other wavelength 02Mould can produce the D of identical size wTherefore, this design a model can be used on＜obtain very little positive dispersion in any required wavelength coverage of 1300nm.
In addition, Fig. 2 chromatic dispersion gradient that draws is zero, negative value or on the occasion of situation, it depends on operation wavelength, wherein the definition of chromatic dispersion gradient is D TotalDerivative with respect to wavelength.Therefore, by means of the notion of complementary ratio, obviously, this kind of design can produce any symbol chromatic dispersion gradient of (comprising zero), meanwhile, and the very little positive dispersion D of generation in the wavelength coverage of＜1300nm Total
Fig. 3 expresses support for the index distribution of the optical fiber of a plurality of moulds, and still, it is designed to produce LP 02The D that mould is required Total, meanwhile, guarantee that also light signal is stable with respect to mode coupling.This index distribution comprises: extending to radial position is the fibre core 30 of 1.1 μ m, and its Δ N equals 0.026; Below be that thickness is the irrigation canals and ditches district 31 of 1.4 μ m, its Δ N equals-0.0087; Below be that thickness is the ring 32 that mixes of going up of 0.7 μ m, its Δ N equals 0.022; Below be that thickness is the irrigation canals and ditches district 33 of 0.7 μ m, its Δ N equals-0.0085; Below be that thickness is the ring 34 that mixes of going up of 1.44 μ m, its Δ N equals 0.015; Below be that thickness is the irrigation canals and ditches district 35 of 1 μ m, its Δ N equals 0.0073.After this, the fibre cladding of only being made by quartz glass 36 extends to the glass-clad edge of this optical fiber.
The LP of waveguide shown in Fig. 4 presentation graphs 3 02The chromatic dispersion D of mould TotalObviously, LP 02Mould has very big positive dispersion, can be up to+100ps/nm-km under the wavelength of 1040nm.In addition, it has positive dispersion in the 120nm span in 1040nm to 1160nm wavelength coverage.
Fig. 5 represents the effective refractive index n that two of optical fiber shown in Figure 3 are not isotype Eff Straight line 50 is LP 02The n of mould Eff, it has very big positive D Total, and it is desirable mode of operation, and straight line 51 is LP 11The n of mould Eff, it has approaches the desirable LP of this optical fiber most 02The n of mould EffValue.In this optical fiber as can be seen, n between two patterns EffDifference in the whole preferred operating wavelength range of 1040nm to 1160nm greater than 10 -4The LP of this optical fiber 02This very large-spacing is arranged between mould and any other guided mode, can guarantee LP 02The light of mould is propagated and is not easy to be coupled to any other mould of this optical fiber, thereby guarantees that light signal has stable, that do not have mode coupling, low-loss propagation.The do not draw n of other guided modes in this optical fiber of Fig. 5 Eff, because them and LP 02The interval of mould even bigger, therefore, the instability that does not have mode coupling to cause.In general, in this optical fiber designs, need to calculate the n of each guided mode usually Eff, and guarantee n between required HOM and any other mould Eff Minimal difference surpass 10 -4
So far, we have described two kinds of typical Refractive Index Profile o, the D that a kind of index distribution produces TotalMaterial dispersion D greater than medium (trace doped dose quartz is normally arranged) m, but in the wavelength coverage of＜1300nm, D Total＜50ps/nm-km.The chromatic dispersion D that another kind of index distribution provides TotalGreater than material dispersion D m, D TotalUnder the wavelength of＜1300nm, have big arbitrarily on the occasion of, therefore, the Δ n between required mould and the parasitic mode EffAlways greater than 10 -4, in order to ensure stable operation.Fig. 6 represents the index distribution of finished product fibre-optical preform, and it produces the LP that satisfies above-mentioned two conditions 02Mould.Fig. 7 represents the LP of optical fiber shown in Figure 6 02Chromatic dispersion (the D of mould Total).On the span of 100nm in the wavelength coverage of 820-920nm, LP 02The chromatic dispersion D of mould Total＜+40ps/nm-km.Therefore, (in about as shown in Figure 2-100ps/nm-km) wavelength coverage, this generation has the optical fiber of low positive dispersion in material dispersion very big negative value to be arranged.Note that dispersion curve shown in Figure 7 (and dispersion curve shown in Figure 2) has the break over region in interested wavelength coverage, that is, and in operation wavelength.
Fig. 8 LP that draws respectively 02Mould (80) and LP 11The n of mould (81) EffAs at Fig. 3, shown in 4 and 5 under the situation of optical fiber, LP 11The n of mould EffApproach most LP in this optical fiber 11The n of mould Eff, therefore, it is enough to study the difference of the two to estimate the ability of their anti-mode couplings.From Fig. 8, can infer n EffPoor (Δ n Eff) in the whole operating wavelength range of 820nm-920nm greater than 10 -4
In all discussion of above-mentioned optical fiber, preferred mode of operation is LP 02Mould.Can implement identical designing technique to produce such optical fiber, wherein propagate and occur in another high-order mode, it has above-mentioned chromatic dispersion and stability characteristic (quality).
Utilize the optical devices of the invention described above optical fiber to need weighted-voltage D/A converter, in order that introduce the preferred mould of light signal to HOM optical fiber.Therefore, the input beam of Gaussian beam space diagram normally, because it is the preference pattern of ordinary optic fibre, and free space beam, must be become preferred HOM by space conversion expeditiously.Utilize the long period fiber grating of suitably design easily to achieve this end, the operation of describing them in US Patent No.6084996 and No.6768835 in detail is as static and dynamic mode converter.The fiber grating weighted-voltage D/A converter can realize being low to moderate the loss of 0.1dB, meanwhile, it provides the mode switch efficient up to 99.99%, give experimentally to show as Ramachandran et al., and at Optics Letters, vol.27, p.698, describe in 2002, its title is " Bandwidth control oflong-period grating-based mode converters in few-mode fibers ".Fig. 9 (a) expression utilizes the exemplary device structure of fiber grating, wherein HOM optical fiber is connected to grating at the input end and the output terminal of this optical fiber, input end and output terminal in order to ensure this device are the common Gaussian beam patterns, even can be different in the inner preferred mode of operation of this device.Light source and the light path represented with arrow can have any suitable wavelengths, but preferably below 1300nm.In addition, the mould image of the common low-order mode (LOM) that in this synoptic diagram, also draws, normally LP 01And required HOM, desirable chromatic dispersion and stable LP are preferably arranged 02According to this configuration, this device can be connected to any other system, no matter it be in laser cavity, require positive dispersion mix the Yb fiber laser, still Ti: the pulse transfer mode of sapphire laser, wherein this device is used in light and penetrates (do not draw in the figure laser instrument and system architecture) after the solid-state laser.Perhaps, Ishaaya et al. is at Optics Letters, vol.30, p.1770, and the discrete phase shift plate of describing in 2005, its title is " Intracavitycoherent addition of single high-order modes ".This synoptic diagram draws in Fig. 9 (b).Several application requires high-power light beam output, and it can be a collimated light beam, rather than the Gaussian beam shape.In these were used, the synoptic diagram of Fig. 9 (c) may be suitable, and wherein suitable weighted-voltage D/A converter converts the Gaussian mode of input to required HOM, but it exports only collimated and relaying in free space.
As described above, fiber device is designed to propagate high-order mode (HOM) in one section optical waveguide, optical fiber preferably, and therefore, the total dispersion in this section optical fiber is greater than the material dispersion in this section optical waveguide.In order to achieve this end, optical waveguide/optical fiber supports the propagation of HOM as main propagating mode, that is, most luminous energy is in preferred HOM.As mentioned above, be retained among the preferred HOM in order to ensure most luminous energy, that is, do not have mode switch, the difference of the effective refractive index of preferred HOM and the effective refractive index of any other mould is at least 0.0001.In order to limit the present invention, there is the optical fiber of this feature can be referred to as less fundamental mode optical fibre, that is, it is to support the basic mode and the optical fiber of another mould at least.
The professional can make various changes to the present invention.Depart from all of this instructions particular content and all should regard as in the scope of described in the invention and application, wherein these depart from and rely on principle of the present invention and suitable content thereof basically.

Claims (33)

1. optical devices comprise:
The optical fiber of first length, this optical fiber has fibre core and covering, and wherein said fibre core is supported first mould,
Weighted-voltage D/A converter, be used for the light of first mould convert in second high-order mode light and
The optical fiber of second length of fibre core and covering is arranged, and wherein this high-order mode is propagated in the fibre core of the optical fiber of second length, and wherein the total dispersion of this high-order mode is greater than material dispersion.
2. the optical devices of claim 1, the effective refractive index of this high-order mode wherein, the effective refractive index with any other mould of propagating in described fibre core differs at least 0.0001.
3. the optical devices of claim 2, wherein the optical fiber of this second length is less fundamental mode optical fibre.
4. the optical devices of claim 2, wherein the total dispersion of this waveguide has the value greater than zero.
5. the optical devices of claim 2, wherein the slope of this total dispersion is positive.
6. the optical devices of claim 2, wherein the slope of this total dispersion is born.
7. the optical devices of claim 2, wherein this total dispersion has the break over region.
8. the optical devices of claim 2, wherein this high-order mode is LP 02
9. the optical devices of claim 2, wherein this weighted-voltage D/A converter is a long-period gratings.
10. the optical devices of claim 2, wherein this weighted-voltage D/A converter is a phase-plate.
11. the optical devices of claim 2 also comprise: the weighted-voltage D/A converter that is used for high-order mode is transformed into low-order mode.
12. an optical fiber has:
Material dispersion; With
Be configured to support the index distribution of high-order mode, this high-order mode is on the wavelength less than about 1300nm, total dispersion greater than material dispersion is arranged, this high-order mode has first effective refractive index, this index distribution also is configured to support second mould, this second mould has second effective refractive index, and this second effective refractive index and first effective refractive index differ at least 10 -4
13. the optical fiber of claim 12, wherein this optical fiber is configured between high-order mode signal propagation periods, produces broadband super continuum light spectrum.
14. the optical fiber of claim 12, this second mould is a basic mode.
15. the optical fiber of claim 12, this second mould is second high-order mode.
16. the optical fiber of claim 12 also is configured between high-order mode signal propagation periods, produces the derivation effect of broadband super continuum light spectrum.
17. the optical fiber of claim 12 also is configured to produce the orphan between high-order mode signal propagation periods.
18. the optical fiber of claim 12, this broadband super continuum light spectrum is produced when the high-order mode signal wavelength is between 820nm and 900nm.
19. the optical fiber of claim 12, this broadband super continuum light spectrum is produced when the high-order mode signal wavelength is between 1040nm and 1160nm.
20. an optical fiber has:
Material dispersion; With
Be configured to support the index distribution of first high-order mode, this first high-order mode is on the wavelength less than 1300nm, total dispersion greater than material dispersion is arranged, this first high-order mode has first effective refractive index, this index distribution also is configured to support other moulds, each other mould has corresponding separately effective refractive index, and each other effective refractive index and first effective refractive index differ at least 10 -4
21. the optical fiber of claim 20, wherein this optical fiber is configured between high-order mode signal propagation periods, produces broadband super continuum light spectrum.
22. the optical fiber of claim 20, these other moulds comprise basic mode.
23. the optical fiber of claim 20, these other moulds comprise second high-order mode.
24. the method in the optical fiber that is used in material dispersion, the step that comprises has:
Wavelength is propagated in high-order mode less than the signal of 1300nm, and this high-order mode has the total dispersion greater than this fiber optic materials chromatic dispersion, and this total dispersion is less than+50ps/nm-km; With
Make between this signal propagation periods, produce broadband super continuum light spectrum.
25. the method for claim 24, the step of this generation broadband super continuum light spectrum also comprises the step that produces the orphan.
26. the method for claim 24, this step that signal is propagated also comprises the step that the signal of wavelength between 820nm and 900nm propagated.
27. the method for claim 24, this step that signal is propagated comprises the step that the signal of wavelength between 1040nm and 1160nm propagated.
28. the method for claim 24 also comprises the step of the derivation effect that produces broadband super continuum light spectrum.
29. one kind is configured to optical fiber that signal is propagated in high-order mode, this optical fiber has:
Material dispersion; With
Greater than the high-order mode total dispersion of this material dispersion, this total dispersion is on the wavelength less than 1300nm, and less than+50ps/nm-km, this optical fiber is configured between this signal propagation periods, produces broadband super continuum light spectrum.
30. the optical fiber of claim 29 also is configured between this signal propagation periods, produces the derivation effect of broadband super continuum light spectrum.
31. the optical fiber of claim 29 also is configured between this signal propagation periods, produces the orphan.
32. the optical fiber of claim 29, this broadband super continuum light spectrum is produced when signal wavelength is between 820nm and 900nm.
33. the system of claim 29, this broadband super continuum light spectrum is produced when the high-order mode signal wavelength is between 1040nm and 1160nm.
CN201010128672A 2006-03-04 2007-03-02 Optical fiber and fiber device that chromatic dispersion is arranged Pending CN101852887A (en)

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